Well I think the batting powerplay could be taken between 10-15 or 15-20 while Tamim is still around and he can just continue firing away. Batsmen will already be in the powerplay frame of mind from the initial 1-10 overs and can take full advantage of the batting powerplay then. Taking the powerplay too late only complicates things or we maybe in a tight/risky situation to take it. 40-50 overs can be utilized in the traditional way where teams used to slog in those overs anyway.